1. Field of the Invention
The present invention relates to a semiconductor package reliability tester, and more particularly, to a POGO pin for testing the electrical characteristics of a semiconductor package and a test socket including the POGO pin.
2. Description of the Related Art
Semiconductor devices that have undergone patterning processes are subjected to an electrical die sorting (EDS) test using a probe unit. After the EDS test, the semiconductor devices are packaged in semiconductor packages via a series of packaging processes. Then, the semiconductor packages are electrically tested using a test socket before they are shipped as products to be sold. The test socket, whose construction and shape may be changed depending on the type or shape of the package to be tested, is used to electrically connect a semiconductor device with a tester board.
FIG. 1 is a sectional view showing a conventional POGO pin 30 positioned between a test board 20 and semiconductor package 10 for testing of the electrical characteristics of the semiconductor package.
Referring to FIG. 1, in a conventional electrical characteristic test, a POGO pin 30 electrically connects a semiconductor package 10 that is being tested with a test board 20. The conventional semiconductor package 10 shown includes a ball grid array (BGA) package having solder balls attached on a surface thereof may be used. The test board 20 supplies the semiconductor package 10 with a test voltage, a test current, a test signal, and the like to precisely determine whether the semiconductor package 10 has an operation failure.
The POGO pin 30 is built into a test socket (see 100 of FIG. 4) and is interposed between the semiconductor package 10 and the test board 20. The POGO pin 30 electrically connects the semiconductor package 10 with the test board 20, as between an electrical terminal 22 on the test board 20 and the solder ball 12 on the semiconductor package 10 to be tested. The POGO pin 30 includes a bar-shaped plunger 35 having a high conductivity and a coil spring 37 wound about a lower portion of the POGO 30.
The plunger 35 includes an upper plunger 32 and a lower plunger 34 formed integrally with the upper plunger 32, with the upper plunger 32 being larger in diameter than the lower plunger 34. The upper plunger 32 has a protruded stopper 33 at a predetermined portion thereof, i.e., at the portion where the upper plunger 32 is connected with the lower plunger 34. The protruded stopper 33 is larger in diameter than the upper plunger 32. The upper plunger 32 also has equiangular protrusions 31 formed at an end thereof so as to facilitate its contact with the solder balls 12. The lower plunger 34 is inserted inside the coil spring 37 which in an unbiased position extends past the end of lower plunger 34 to contact an electrical terminal 22 of the test board 20.
One drawback of the convention POGO pin 30 as shown in FIG. 1 is problems incurred when shorter contacting test pins are required. If the conventional POGO pin 30 is manufactured having a length below 3 mm, the life span of the POGO pin 30 is severely shortened, making it difficult to use. However, it is preferable that the POGO pin 30 be short when testing radio frequency (RF) products. This is because RF signals are greatly affected by parasitic inductance and capacitance. Accordingly, the conventional POGO pin 30 is not suitable for testing RF products.
An alternate design for RF testing known in the art includes using a conductive rubber member. FIG. 2 is a sectional view illustrating such an alternate design using a unitary rubber contact pin 50.
Referring to FIG. 2, the rubber contact pin 50 includes a first contact pin 51 contacting a solder ball 12 of a semiconductor package 10, and a second contact pin 55 opposing the first contact pin 51 and contacting an electrode terminal 22 of a test board 20. The first contact pin 51 and the second contact pin 55 are connected to each other by a conductive rubber member 53 having an elastic force and formed of a mixture of silicon rubber and a conductive powder.
Because the rubber contact pin 50 is short in length, it is possible to sufficiently test RF products. Also, the rubber contact pin 50 has the advantage of being able to precisely contact all packages—even a package without a solder ball design—for example, a line grid array (LGA) package. However, the rubber contact pin 50 used in the prior art has the disadvantage of a short life span due to use of the rubber material.